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The exponential accumulation of post-consumer plastic poses a critical global environmental challenge, necessitating the development of effective and efficient recycling strategies. This dissertation investigates different pyrolysis approaches for recycling diverse plastic waste streams including medical waste, single type commodity plastics, and complex mixtures to co-produce hydrogen and valuable carbon materials. The work starts with the catalytic performance study of perovskite-type La₀.₆Ca₀.₄Co₁₋ₓFeₓO₃₋δ pre-catalysts in the conventional thermal catalytic pyrolysis of medical plastic waste. This study identifies the influence of reaction temperature and catalyst composition on product yields, selectivity and the graphitic quality of deposited carbon nanomaterials. While effective, the results from thermal approach highlighted the need for higher energy efficiency which can be achieved by faster reaction kinetics. To address the conversion limitations of thermal processes and further increase the yields of desired products, the second phase of this work introduces an innovative plasma-enabled strategy. It demonstrates that a catalyst-free plasma pyrolysis process can decompose the same amount of plastics into hydrogen and valuable carbon materials in much shorter time with better product yields compared to conventional thermal methods, resulting in significantly higher energy yields. To further enhance the product yields, selectivity, and improve the quality of generated carbon materials, the plasma process was coupled with a thermal catalytic stage using single-atom catalysts M/CeO₂ (M = Fe, Co, and Ni). Density functional theory (DFT) calculations were performed and combined with the experimental results to understand the catalytic mechanisms. Results reveal that the dehydrogenation of two primary by-products, ethylene (C₂H₄) and acetylene (C₂H₂), is most thermodynamically favorable over Co/CeO₂ catalyst among the studied catalysts. This mechanism maximizes hydrogen production, aligning well with the experimental results. Finally, bridging the findings of the previous studies, the robust perovskite-type pre-catalysts La₀.₆Ca₀.₄Co₁₋ₓFeₓO₃₋δ were introduced into the tandem plasma-thermal catalytic process. The impact of different catalyst synthesis methods was investigated. Results indicate that the enhanced catalytic performance can be attributed to the unique spherical morphology formed during ultrasonic spray synthesis (USS). Furthermore, the life cycle assessment (LCA) confirms that USS is a more environmentally sustainable synthesis method for the studied pre-catalysts. Collectively, this dissertation provides promising pathways for converting post-consumer plastic waste into clean energy and valuable materials, offering scalable and sustainable strategies for the circular economy.